Though I thought about it multiple times, I never understood Parmenides' argument for the impossibility of change. Now studying Aristotle's Physics, it popped up again and I still have the same problems – including with Aristotle's criticism of it, which seems like taking a sledgehammer to crack a nut.
Parmenides' argument seems so obviously wrong – not in the sense of Zeno's paradoxes, that cleverly seduce analytical thinking to go astray and rebel against common-sense, but in a trivial sense: effortlessly the argument is recognized as extremely faulty.
When Parmenides claims that change involves something to come from non-being into being, he's really talking about the transformation of something that already exists. So it is not the case that non-being generates being.
I suspect that the argument had much more force in his time. Maybe the question “where” the red of a fruit which ripens comes from was more puzzling?
But today our thinking is heavily influenced by reductionism (I tried to get into Aristotle's mindset, which is holistic, but old habits are difficult to shake): There are chemical processes in the fruit, a bit crudely it's just atoms “moving around” – and those atoms already existed the whole time. No mystery.
Aside from the original version I also read modern paraphrasings, which are supposed to be more rigorous and terminologically clear, so this is not the problem (like in thisthis question), but I still do not get the gist of it.
Could you give me an explanation (or an example) which makes Parmenides argument have more force even in the context of a modern reductionist worldview?